Bug 217427

I'm using Gentoo Linux on a Raptor CS Talos 2 ppc64le, GPU is an AMD RX 570. So far the past dozen of kernels (up to 6.2.14) worked flawlessly, but with 6.3.1 I don't get any video output and I get the following in journalctl:

May 10 15:09:01 talos2 kernel: Kernel attempted to read user page (1128) - exploit attempt? (uid: 0)
May 10 15:09:01 talos2 kernel: BUG: Unable to handle kernel data access on read at 0x00001128
May 10 15:09:01 talos2 kernel: Faulting instruction address: 0xc00800000d1a805c
May 10 15:09:01 talos2 kernel: Oops: Kernel access of bad area, sig: 11 [#1]
May 10 15:09:01 talos2 kernel: LE PAGE_SIZE=4K MMU=Radix SMP NR_CPUS=512 NUMA PowerNV
May 10 15:09:01 talos2 kernel: Modules linked in: rfkill(+) 8021q garp mrp stp llc binfmt_misc amdgpu uvcvideo uvc videobuf2_vmalloc videobuf2_memops gpu_sched snd_hda_codec_hdmi i2c_algo_bit at24(+) videobuf2_v4l2 drm_ttm_helper regmap_i2c videobuf2_common ttm snd_usb_audio drm_di>
May 10 15:09:01 talos2 kernel: CPU: 0 PID: 188 Comm: kworker/0:3 Not tainted 6.3.1-gentoo-dist #1
May 10 15:09:01 talos2 kernel: Hardware name: T2P9S01 REV 1.01 POWER9 0x4e1202 opal:skiboot-9858186 PowerNV
May 10 15:09:01 talos2 kernel: Workqueue: events_long drm_dp_check_and_send_link_address [drm_display_helper]
May 10 15:09:01 talos2 kernel: NIP:  c00800000d1a805c LR: c00800000d1a8018 CTR: c000000000c87900
May 10 15:09:01 talos2 kernel: REGS: c00000000beb3370 TRAP: 0300   Not tainted  (6.3.1-gentoo-dist)
May 10 15:09:01 talos2 kernel: MSR:  900000000280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 88048223  XER: 0000005a
May 10 15:09:01 talos2 kernel: CFAR: c000000000c87980 DAR: 0000000000001128 DSISR: 40000000 IRQMASK: 0 
                               GPR00: c00800000d1a8018 c00000000beb3610 c00800000d690f00 0000000000000000 
                               GPR04: 0000000000000002 c00800000d6297c0 0000000000000000 c00000002a00b740 
                               GPR08: 0000000000000000 0000000000001124 0000000000000000 c00800000d431560 
                               GPR12: c000000000c87900 c000000002a6b000 c000000000170ad8 c00000001a460310 
                               GPR16: 0000000000000045 c000000022858388 c000000026000340 0000000000000001 
                               GPR20: 0000000000000000 0000000000000001 c0000000260001a0 0000000000004000 
                               GPR24: 0000000000004000 c000000026000010 c0000000228580b8 fffffffffffffffd 
                               GPR28: 0000000000000000 c0000000228580a0 c000000022856000 c000000022858000 
May 10 15:09:01 talos2 kernel: NIP [c00800000d1a805c] is_synaptics_cascaded_panamera+0x244/0x600 [amdgpu]
May 10 15:09:01 talos2 kernel: LR [c00800000d1a8018] is_synaptics_cascaded_panamera+0x200/0x600 [amdgpu]
May 10 15:09:01 talos2 kernel: Call Trace:
May 10 15:09:01 talos2 kernel: [c00000000beb3610] [c00800000d1a8018] is_synaptics_cascaded_panamera+0x200/0x600 [amdgpu] (unreliable)
May 10 15:09:01 talos2 kernel: [c00000000beb36d0] [c00800000b7c2b18] drm_helper_probe_single_connector_modes+0x230/0x698 [drm_kms_helper]
May 10 15:09:01 talos2 kernel: [c00000000beb3810] [c000000000c57174] drm_client_modeset_probe+0x2b4/0x16c0
May 10 15:09:01 talos2 kernel: [c00000000beb3a10] [c00800000b7c7a30] __drm_fb_helper_initial_config_and_unlock+0x68/0x640 [drm_kms_helper]
May 10 15:09:01 talos2 kernel: [c00000000beb3af0] [c00800000b7c5b08] drm_fbdev_client_hotplug+0x40/0x1d0 [drm_kms_helper]
May 10 15:09:01 talos2 kernel: [c00000000beb3b70] [c000000000c55480] drm_client_dev_hotplug+0x120/0x1b0
May 10 15:09:01 talos2 kernel: [c00000000beb3c00] [c00800000b7c1130] drm_kms_helper_hotplug_event+0x58/0x80 [drm_kms_helper]
May 10 15:09:01 talos2 kernel: [c00000000beb3c30] [c00800000b80b298] drm_dp_check_and_send_link_address+0x330/0x3a0 [drm_display_helper]
May 10 15:09:01 talos2 kernel: [c00000000beb3cd0] [c000000000162d84] process_one_work+0x2f4/0x580
May 10 15:09:01 talos2 kernel: [c00000000beb3d70] [c0000000001630b8] worker_thread+0xa8/0x600
May 10 15:09:01 talos2 kernel: [c00000000beb3e00] [c000000000170bf4] kthread+0x124/0x130
May 10 15:09:01 talos2 kernel: [c00000000beb3e50] [c00000000000dd14] ret_from_kernel_thread+0x5c/0x64
May 10 15:09:01 talos2 kernel: --- interrupt: 0 at 0x0
May 10 15:09:01 talos2 kernel: NIP:  0000000000000000 LR: 0000000000000000 CTR: 0000000000000000
May 10 15:09:01 talos2 kernel: REGS: c00000000beb3e80 TRAP: 0000   Not tainted  (6.3.1-gentoo-dist)
May 10 15:09:01 talos2 kernel: MSR:  0000000000000000 <>  CR: 00000000  XER: 00000000
May 10 15:09:01 talos2 kernel: CFAR: 0000000000000000 IRQMASK: 0 
                               GPR00: 0000000000000000 c00000000beb4000 0000000000000000 0000000000000000 
                               GPR04: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
                               GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
                               GPR12: 0000000000000000 0000000000000000 c000000000170ad8 c00000000a8fb240 
                               GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
                               GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
                               GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
                               GPR28: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
May 10 15:09:01 talos2 kernel: NIP [0000000000000000] 0x0
May 10 15:09:01 talos2 kernel: LR [0000000000000000] 0x0
May 10 15:09:01 talos2 kernel: --- interrupt: 0
May 10 15:09:01 talos2 kernel: Code: 41820094 e91f0568 e95f0000 813f0088 81080030 3d4a0001 39290444 e94a7ca0 79291764 1d0811f0 7d4a4214 7d2a4a14 <81290004> 91270074 813f0088 39290424 
May 10 15:09:01 talos2 kernel: ---[ end trace 0000000000000000 ]---
May 10 15:09:01 talos2 kernel: at24 4-0054: supply vcc not found, using dummy regulator